Assorted Chemistry Syllabus Points

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4.e Analyse information from secondary sources to assess the use of neutralisation reactions as a safety measure or to minimise damage in accidents of chemical spills
The neutralisation of acids and bases is an exothermic reaction, meaning it releases heat energy during a reaction. This makes an unsuitable method to remove the damage of chemical spills on the skin as this will cause severe burns. A better way would be to wash the spill with water. If the spill has not come into contact with a living thing or heat sensitive substance then the spill can be cleared by neutralisation. Weak acids and bases such as sodium hydrogen carbonate and acetic acid can be used. The strength of these weak acids means that they will not release as much heat energy during neutralisation reactions than stronger substances.

4.9 Qualitatively describe the effect of buffers with reference to a specific example in a natural system.
Buffers are solutions that can resist or minimise a change in pH of a system. They are created from the mixing of an acid and its conjugate base or a base and its conjugate acid. The addition of an acid into the system would cause the buffer to form more base to counter this and the addition of a base would cause the formation of an acid. In a solution of carbonic acid and sodium bicarbonate (which occurs naturally in the blood), if hydrogen ions are introduced, the bicarbonate ions (HCO3-) will neutralise these ions and the equilibrium in the system will shift to minimise the introduction of the ions. If a base is added, the carbonic acid acid will form water and bicarbonate ions to minimise this addition.

H2CO3(aq) ↔ H+(aq) + HCO3-(aq)

5.b Process information from secondary sources to identify and describe the uses of esters as flavours and perfumes in processed foods and cosmetics
All esters have a distinctive smell or odour, usually resembling fruit. Esters with lower molecular weights are volatile liquids, meaning the evaporate easily. These are reasons why they are used in perfumes, to give them a fruity smell. There neutrality also makes them safe to use for use on people. They are also used extensively in edible items such as ice creams and sweets.

1.1 Outline the role of a chemist employed in a named industry or enterprise, identifying the branch of chemistry undertaken by the chemist and explaining a chemical principal that the chemist uses
In the plastics industry, a chemist may take the role of lab manager in a plant that creates low density polyethylene (LDPE). The chemist is using the hydrocarbons branch of chemistry as polyethylene is a hydrocarbon. This chemist would be involved in predicting the properties of polymers, using computer equipment, based on temperatures and catalysts. They would monitor production equipment to check that the correct conditions are being maintained to create a polymer. They would conduct quality control experiments on portions of the final product to ensure it meets expectations and requirements. For example, the scientist would conduct a density and viscosity test to find the amount of branching and the suitability for film blowing. They would also evaluate techniques to improve efficiency and quality of products and the creation of new products.

1.2 Identify the need for collaboration between chemists as they collect and analyse data
When scientists work in a team, the different members will have differing knowledge of chemistry. Not having different knowledge would defeat the purpose of a team. Therefore, each member of the team will have separate and most likely important contributions to the investigations of the team. If the team does not collaborate, the investigations will be hampered by limited knowledge and non co-operation. This can severely affect the research of the team and stop them from producing a useful result.

1.3 Describe an example of a chemical reaction such as combustion, where reactants form different products under different conditions and thus would need monitoring
During the combustion of methane, the amount of oxygen used in the reaction will affect the final products. When lots of oxygen is used, the reaction forms carbon dioxide and water.
When slightly less oxygen is used, the reaction forms carbon monoxide and water.
If hardly any oxygen is used (the hole on the bunsen burner is closed), the reaction will produce solid carbon and water.
This reaction changes based on conditions and therefore needs to be monitored by scientists when utilised.

1.a gather, process and present information from a secondary source about the work of practising scientists identifying: - the variety of chemical occupations - a specific chemical occupation for a more detailed study
Research - Chemists can cary out research into new elements, compounds, reactions of these matter particles and applications of these discoveries.
Applied Research - Use the information of researchers to find uses of discoveries in industry, medicine etc.
Chemical Manufacturing - Chemistry in industry, for example, the creation of compounds in a cheaper, more efficient way, quality control of compounds.
Analytical Chemistry - Analysis of new compounds to find their composition, quality control, chemical makeup of substances such as air.
Biochemistry - The study of biological molecules in living things.
Chemical Engineering - Designing the equipment and machinery that will cause reactions/manufacture of compounds and monitoring of this process.
Physical Chemistry - The properties of particles, how chemical reactions work.
Radiochemistry - A chemist who deals with the nuclear transformations of elements involving nuclear radiation. This can be applied to the creation of new elements through bombardment and decay or for use in medical applications such as blood tracers. They can also be used in the treatment of diseases. Radiochemists can find find jobs in the pharmaceutical industry to create these drugs. They can also be applied to the energy industry.

2.1 Identify and describe the industrial uses of ammonia
Ammonia is a key component of many fertilisers used on food crops to help feed people.
It is also used in the production of explosives, particularly in the First World War when the Germans had their nitrate imports blocked by the British. Ammonia is also the starting pint for many other chemicals.

2.2 Identify that ammonia can be synthesised from its component gases nitrogen and hydrogen
Ammonia can be synthesised from Nitrogen and hydrogen through process of synthesis called the Haber process. It involves high temperatures and pressures.
Natural gas is used to produce hydrogen. Sulphur compounds are removed so they do not poison the metal catalysts. It is compressed to 30 atm and reacts with steam (nickel catalyst) at 750 degrees to produce hydrogen and carbon oxides.

2.3 Describe that synthesis of ammonia occurs as a reversible reaction that will reach equilibrium
When nitrogen and hydrogen are reacted to from ammonia and energy, the reaction is an equilibrium reaction. Ammonia can be decomposed back into nitrogen and hydrogen. Equilibrium reactions reach equilibrium when conditions allow it, or when the system is undisturbed.

2.4 Identify the reaction of hydrogen with nitrogen as exothermic
The creation of ammonia from nitrogen and hydrogen is an exothermic reaction.

2.5 Explain why the rate of reaction is increased by higher temperature
In an equilibrium reaction of ammonia:

N2(g) + 3H2(g) ↔ 2NH3(g)

An increase in pressure in the system will push the reaction to the right. Because this reaction is exothermic, an increase in heat energy will push the equation to the left. This means the decomposition of ammonia occurs. Higher temperatures increases pressure and makes the reaction occur faster.

2.6 Explain why the yield of product in the Haber process is reduced at higher temperatures using Le Chatelier’s principle

N2(g) + 3H2(g) ↔ 2NH3(g)

The above equation is an exothermic reaction. When temperature is increased, the equation is pushed towards the left because it is an equilibrium reaction: the system adjustst to remove as much of the disturbance as possible. The process of reversing this disturbance means that ammonia decomposes, reducing the yield.

2.7 Explain why the Haber process is based on a delicate balancing act involving reaction energy, reaction rate and equilibrium
Reaction energy and reaction pressure both greatly affect the reaction rate and yield because of the equilibrium property of the Haber process. An increased pressure increases the yield of the reaction while increased temperature increases reaction rate and decreases yield. An appropriate balance must be found to maximise the yield at an acceptable rate for industry.

2.8 Explain that the use of a catalyst will lower the reaction temperature required and identify the catalyst(s) used in the Haber process.
Lowering the temperature of the reaction for the Haber process is done by introducing a catalyst into the reaction. The catalyst increase the speed that an equilibrium between the products and reactants is reached. This means that a higher temperature is not needed to increase reaction speed. A lower temperature allows for more ammonium production. An example of the catalysts used in this reaction is iron oxide, potassium oxide and aluminium oxide.

2.9 Analyse the impact of increased pressure on the system involved in the Haber process.
Increasing pressure during the Haber process pushes the equilibrium reaction to the right, increasing the production of ammonia. A balance must be formed between huge pressures in the reaction vessel and low pressures. At low pressures, not enough ammonia will be formed but and higher pressures, the vessel containing the gas may explode.

2.10 Explain why monitoring of the reaction vessel used in the Haber process is crucial and discuss the monitoring required
Not monitoring the equipment and environment that is used in the Haber process could result in abnormal products or no products at all. The pressure in the vessel must not be too large so the vessel does not explode, but it must be high enough to form enough product to be viable. The temperature must be high enough to produce ammonia at a high enough rate but not too high so that hardly any product is formed. The amount of ammonia being produced must also be carefully monitored to find any problems that may be occurring. Rates of the gases and evenness of the gases must also be carefully monitored to ensure the reaction continues at optimum level. The catalyst pellets must be checked for size, they must be small enough to have a large surface area and large enough for gas to flow easily. All equipment must be checked for clogging and the ammonia must be quality control tested to ensure customers are satisfied.

2.a Gather and process information from secondary sources to describe the conditions under which Haber developed the industrial synthesis of ammonia and evaluate its significance at that time in the world
The process was created by Haber and Bosch while they worked at a German chemical company in 1910. They had to work with temperatures and pressures that were very high for the day which was hard to deal with and took extra time. It was also more dangerous and so extra time had to be taken to check all safety measures.
The synthesis of ammonia was an important step in the industrial production of nitrate products, namely explosives and fertilisers. It meant that the production of these materials no longer needed to be from natural deposits of nitrates, for example sodium nitrate. Chile was the only producer of sodium nitrate at the time so the price for producing these products was enormous. The synthesis of ammonia led to easier and cheaper production of fertilisers and explosives which were necessary for the upcoming World War. The invention of this technique may have helped Germany to enter the War.